Eccentric system for vibratory earth compactor

ABSTRACT

An eccentric system for a vibratory apparatus, such as an earth compactor, comprising a tube having end closures, bearings respectively supporting the end closures for rotation of the end closures and the tube about the axis of the tube, and an eccentric bar within and extending longitudinally of and spaced radially inwardly from the tube, the eccentric bar having ends coaxial with the tube and respectively carried by the end closures of the tube. The tube, its end closures and the eccentric bar constitute an eccentric shaft which, together with its bearings, is enclosed by an outer housing. Impellers at the ends of and rotatable with the eccentric shaft circulate a lubricant, such as oil, between the interior of the tube and the outer housing by way of the bearings, thereby lubricating and cooling the bearings continuously. Air in the structure is also circulated through the bearings by the impellers for cooling purposes.

United States Patent 1 "[111 3,721,129 Wallick 45]March 20, 1973 [54]ECCENTRIC SYSTEM FOR Primary Examiner-Milton Kaufman VIBRATORY EARTHCOMPACTOR Paul C. Wallick, Long Beach, Calif.

A-T-O Inc Willoughby, Ohio Inventor:

Assignee:

Filed: Aug. 13, 1971 Appl. No.: 171,567

US. Cl ..74/87, 74/61, 94/50 V, 259/DIG. 42

Int. Cl. ..B06b 1/16 Field of Search ..74/87, 61; 94/50 V, 48; 209/3665,367; 259/DIG. 42

References Cited UNITED STATES PATENTS Attomey-Harris, Kern, Wallen 8LTinsley ABSTRACT about the axis of the tube, and an eccentric bar withinand extending longitudinally of and spaced radially inwardly from thetube, the eccentric bar having ends coaxial with the tube andrespectively carried by the end closures of the tube. The tube, its endclosures and the eccentric bar constitute an eccentric shaft which,together with its bearings, is enclosed by an outer housing. Impellersat the ends of and rotatable with the eccentric shaft circulate alubricant, such as oil, between the interior of the tube and the outerhousing by way of the bearings, thereby lubricating and cooling thebearings continuously. Air in the structure is also circulated throughthe bearings by the I impellers for cooling purposes.

10 Claims, 5 Drawing Figures SHEET 10F 2 PATENTEDHARZO I975 MIl EA/TORPAUL C. MLL/CK er HA5 ATTOEA/E K5 HAxz/z/s, A7504 Passe-u. & KERNECCENTRIC SYSTEM FOR VIBRATORY EARTH COMPACTOR BACKGROUND OF INVENTIONThe present invention relates in general to an eccentric system forinducing vibration in a vibratory apparatus. Since the invention isparticularly applicable to a vibratory roller of an earth compactor, itwill be considered in such connection herein as a matter of convenience.Vibrating an earth compacting roller can be an economical means ofincreasing compaction production by more effectively utilizing theweight of the roller. Although an asset in the sense that it increasescompaction production, vibration can be a liability in equipmentoperation. If not properly employed, vibration tends to destroy not onlythe eccentric system which produces it, but the equipment to which thevibration is applied. Failure to utilize vibration properly has beenresponsible for much lack of efficiency and reliability in the earthcompacting field.

SUMMARY AND OBJECTS OF INVENTION With the foregoing background in mind,a primary object of the invention is to provide an eccentric system,particularly adapted for an earth compacting roller, which is capable ofproducing high frequencies and forces (or amplitudes) reliably at areasonable cost.

More particularly, an important object of the invention is to provide aneccentric system which requires a very low starting effort, reducesoperating power levels to a minimum, requires a minimum of maintenance,and extends bearing life to a maximum.

Still more specifically, a basic object of the invention is to providean eccentric shaft which deflects negligibly at its supporting bearingsduring rotation so that the bearing wear resulting from eccentric shaftdeflection in conventional systems is virtually eliminated.

Still another important object is to provide an eccentric shaft whichachieves negligible deflection with a minimum moment of inertia, therebyminimizing starting effort and power requirements.

Still another important object is to provide an eccentric shaft whichachieves negligible deflection at the bearings, thus allowing theapplication of cylindrical roller bearings rather than spherical rollerbearings as are necessary for shafts which deflect. Cylindrical bearingsare inherently tolerant of eccentric shaft growth relative to eccentrichousing growth resulting from shaft heating and consequently do notdevelop the high thrust loads which are the principal cause of failuresin spherical bearing applications, an important feature.

The foregoing basic objects of the invention may be achieved byproviding, and another object of the invention is to provide, acomposite eccentric shaft which includes: a relatively rigid or stifftube; end closures for the tube which are supported by bearings forrotation of the tube and end closures about the axis of the tube; and arelatively flexible, low inertia, eccentric bar within and extendinglongitudinally of and spaced radially inwardly from the tube, thiseccentric bar having ends coaxial with the tube and respectivelyconnected to the end closures of the tube.

With the foregoing construction, the eccentric bar flexes to aconsiderable degree, e.g., 10 times as much as conventional eccentricshafts. However, the large forces produced by the eccentric bar aretransmitted through the rigid housing end closures on a line which isvery close to the center line of the bearings. The line of force isslightly offset from the center line of the bearing. The offset iscalculated to produce a bending moment in the rigid housing. This momentmagnitude and direction is set to nullify the bending moment resultingfrom the orbital motion of the rigid tube. As a result, the compositeeccentric shaft of the invention is capable of producing the sameeccentric forces with less than half the inertia, and only about onepercent of the deflection at the bearings, of conventional eccentricshafts, which is an important feature.

Still another important object is to provide a composite eccentric shaftof the foregoing nature capable of being so mounted in an earthcompacting roller or drum that drum growth in use will not detrimentallyaffect bearing spacing and alignment.

A further object of considerable importance is to en close the compositeeccentric shaft and its bearings in an outer housing and to providemeans for circulating a lubricant through the eccentric tube, andbetween the eccentric tube and outer housing, as a means of providingdependable, continuous, clean and controlled flow of lubricant and airthrough the bearings.

More particularly, an important object in connection with thelubricating system of the invention is to provide impellers, adjacentthe bearings and rotatable with the composite eccentric shaft, forcirculating air as a means of circulating a small flow of lubricant inthe form of lubricant droplets entrained in the air through thebearings.

Yet another object is to provide a lubricating system wherein the endclosures are provided with inlet ports communicating with the impellersand through which the impellers pump the lubricant into the tube of theeccentric shaft, lubricant metering ports communicating with thebearings being provided to meter the lubricant to the bearings.

A further object is to provide air discharge ports in the tube for thedischarge of air pumped into the tube through the inlet ports by theimpellers, whereby air circulation throughout the eccentric shaft, itsbearings and the outer housing is established for cooling purposes.

A still further object is to provide a highly reliable bearinglubrication system. This is achieved by the combined effects of thefollowing features:

1. Lubricant cleaning-all the lubricant flows from the shaft inlet portsto the orifice duct inlets and the air vent oil discharge ports, nearthe center of the eccentric shaft. During the time (several minutes)required to traverse this distance, contaminants in the oil areseparated out and deposited on the eccentric tube wall by highcentrifugal forces (approximately 700 times gravity), thus assuring aflow of centrifugally cleaned oil to the bearings.

2. Constant and equal lubricant flow to the eccentric bearings isassured regardless of shaft attitude by the uniform distribution oflubricant along the full length of the inside of the eccentric shafttube as a result of the high ratio of centrifugal to gravitationalforce.

3. Lubricant loss rate is very low due to the housing configurationwhich requires only one relatively small diameter shaft seal. This seal,on the eccentric drive shaft, is very reliable since it operates at lowsurface speeds, is subjected to moderate temperatures, and is notsubject to external abrasion due to its location inside the roll stubshaft.

4. Lubricant orifice fouling protection-orifice fouling is prevented byfilter material packed upstream of the orifice in the orifice duct, bythe centrifugal cleaning action which settles out contaminants near theshaft ends-well away from the orifice duct inlets, and further bylocating the orifice inlet duct above the eccentric bar away from thecontaminants which settle below the eccentric bar when the eccentric isidle.

5. Lubricant coolinglubricant cooling is critical to the life of thelubricant and hence to the life of the bearings. Oil cooling capacityindirectly affects bearing heat generation since most bearing heat isproduced by the lubricant itself. The lubricant flow rate and heatgeneration increases as lubricant viscosity drops with increase intemperature. Proper lubricant cooling capacity is thus required tomaintain the lubricant at an acceptable temperature. Lubricant heat isdissipated in the following ways:

a. Heat is lost directly to cooler oil in the eccentric shaft as itmoves from the ports at the ends to the center of the eccentric shaft.

b. Heat is lost by the lubricant along the full length of the eccentricshaft by radiation and air convection to the eccentric housing.

0. Eccentric housing heat is transmitted to the roll by radiation andconduction when not water ballasted, and by direct water convection whenballasted. When partially ballasted water is splashed over the eccentrichousing by angles acting as water transports.

The foregoing objects, advantages, features and results of the presentinvention, together with various other objects, advantages, features andresults which will be evident to those skilled in the art in the lightof this disclosure, may be achieved with the exemplary embodimentillustrated in the accompanying drawings and described in detailhereinafter.

DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 is an elevational view of a vibratory earth compacting rollerequipped with the invention;

FIG. 2 is an enlarged, fragmentary longitudinal sectional view taken asindicated by the arrowed line 2-2 of FIG. 1;

FIG. 3 is a further enlarged, transverse sectional view taken asindicated by the arrowed line 3-3 of FIG. 2 of the drawings;

FIG. 4 is a transverse sectional view taken as indicated by the arrowedline 4-4 of FIG. 1; and

FIG. 5 is an enlarged fragmentary sectional view taken as indicated bythe arrowed line 5--5 of FIG. 3 and duplicating a portion of FIG. 2 on alarger scale.

DESCRIPTION OF EXEMPLARY EMBODIMENT OF INVENTION Referring initially toFIG. 1 of the drawings, designated generally therein by the numeral 10is a vibratory earth compacting roller which has a smooth surface in theparticular construction illustrated. However, it may also be of thesheeps foot type if desired.

Referring to FIG. 2 for the moment, the roller 10 is provided at itsends with headers 12 which carry axially-outwardly projecting stubshafts l4 rotatable relative to suitable roller supports 16 in bearings18. As is well known in this art, the roller supports 16 are connectedto an earth compacting vehicle, not shown, through suitable vibrationisolating structures, not shown.

Disposed within and coaxial with the roller 10 is a rigid, tubulareccentric housing 20 which is rigidly connected at its ends to theroller headers 12 and the stub shafts 14 in any suitable manner. As willbecome apparent, the ends 22 of the eccentric housing 20 containbearings 24 for an eccentric shaft 26 of the invention. Thus, theeccentric housing 20 permanently fixes the axial spacing and alignmentof the eccentric bearings 24 so that there is no change in therelationship between these bearings with growth of the roller or drum10, which is an important feature of the invention. Drum growth in useis accommodated by distortion of the headers 12.

The eccentric shaft 26 is a composite structure which includes arelatively stiff, rigid tube or tubular housing 28 having end closures30 secured thereto, as by welding. The end closures 30 comprise stubshafts which extend into the bearings 24 to mount the tube 28 and itsend closures 30 for rotation about the axis of the tube. The eccentricshaft 26 is driven by a coaxial drive shaft 32 having a splinedconnection to one of the end closures 30. The drive shaft 32 is suitablyrotatably mounted within the corresponding roller stub shafts 14, and isequipped at its outer end with a drive sheave 34.

The composite eccentric shaft 26 also includes an eccentric bar 36within and extending longitudinally of and spaced radially inwardly fromthe eccentric shaft tube or housing 28. The eccentric bar 36 is providedwith ends 38 coaxial with the tube 28 and respectively carried by theend closures 30. The eccentric bar 36 is suitably connected to the endclosures 30, as by pins 40, so that the eccentric bar rotates with thetube 28 and the end closures 30 about the axis of the tube.

With the foregoing construction, the eccentric bar 36, which isrelatively flexible, can flex to a considerable extent during rotationof the eccentric shaft. However, the rigid eccentric shaft housing 28virtually eliminates any deflection of the composite eccentric shaft 26at the eccentric bearings 24, thereby maximizing bearing life, which isan important feature. Also, the eccentric bar 36 has a relatively lowmoment of inertia, with the result that the composite eccentric shaft 26requires a very low starting effort and requires minimum power inoperation, which are additional important features.

Turning now to another aspect of the invention, coaxial with theeccentric shaft housing 28, and suitably fixed on the stub shafts formedby the end closures 30 thereof, are impellers 42 located adjacent andaxially outwardly of the eccentric bearings 24. As will be discussed inmore detail hereinafter, the impellers 42, in response to rotation ofthe eccentric shaft 26, draw fluid through the eccentric bearings 24into toroidal chambers 44 in the inner ends of the roller stub shafts14. The chambers 44 communicate with the annulus 46 between theeccentric housing 20 and the eccentric shaft 26 through the eccentricbearings 24. They also communicate with the interior of the eccentricshaft housing 28 through inlet ports 48 in the end closures 30. Thelatter also carry plugs 49 provided with relatively small, meteringoutlet ports 50, FIG. 5, which communicate with the eccentric bearings24 and which are located radially inwardly of the eccentric shaft tubeor housing 28. The plugs 49 are interconnected by a longitudinal tube 51having central lubricant inlets 53, FIG. 2, and containing a filteringmateria155, FIG. 5, such as stainless steel wool, at each end.

The eccentric shaft housing 28 is provided intermediate its ends withradially-inwardly extending vents 52 interconnecting the interior of thehousing 24 and the annulus 46. These vents are also provided with ports54 intermediate their outer and inner ends, as best shown in FIG. 3.

Disposed within the eccentric system defined by the eccentric housing 20and the eccentric shaft 26 therein is a quantity of liquid lubricant,such as oil. During rotation of the eccentric shaft 26, the oil withinthe eccentric shaft is displaced radially outwardly by centrifugalforce, and, as shown in FIG. 3, occupies the space radially outwardly ofthe dotted line 56. This annular body of oil is under pressure becauseof the centrifugal force acting thereon, with the result that oil flowsfrom the eccentric shaft housing 28 through the tube 51 and the meteringports 50 and into the eccentric bearings 24, thereby lubricating thebearings continuously as long as the eccentric shaft is rotating, whichis an important feature. Since the tube 51 is spaced radially inwardlyfrom the eccentric shaft housing 28, solid contaminants in the oil areheld against the housing 28 by centrifugal force and cannot flow throughthe tube 51 into the eccentric bearings 24. Any contaminants that doenter the tube 51 through its inlet ports 53 are filtered out by thefilters 55. Consequently, frequent changing of the oil and flushing ofthe eccentric system are unnecessary. The relatively long tube 51requires all the oil to flow to the center of the eccentric shaft 26before reaching the bearings 24, thereby producing better cooling. Stillanother feature is that the centrifugally induced oil pressure insuresproper bearing lubrication, even if the roller is on a slope with onebearing 24 above the other.

The oil flowing from the metering ports 50 through the eccentricbearings 24 is returned to the interior of the eccentric shaft 26through the inlet ports 48 by the impellers 42, the circulation of oilthroughout the eccentric system being indicated by solid arrows in FIGS.2 and 3 of the drawings. Some of the oil inthe centrifugally formed oilannulus within the eccentric shaft 26 flows through the ports 54 and thevents 52 into the an nulus 46 between the eccentric housing 20 and theeccentric shaft housing 28. This oil is cooled by contact with theeccentric housing 20, which is an important feature, and is returned tothe interior of the eccentric shaft 26 by the impellers 42, by way ofthe eccentric bearings 24 and the inlet ports 48. Thus, the ports 54 inthe vents 52 provide a further metered flow of cooled oil to theeccentric bearings 24.

In addition to the oil, the impellers 42 circulate cooling airthroughout the eccentric system, as indicated generally by the brokenarrows. More particularly, the cooling air circulated by the impellers42 flows into the eccentric shaft 26 through the inlet ports'48, andthen escapes into the annulus 46 through the vents 52. While in theannulus 46, the air is cooled by contact with the eccentric housing 20,and returns to the impeller chambers 44 by way of the eccentric bearings24.

Thus, the eccentric system of the invention is provided with a closedlubricating and cooling system, the oil and the air within the systembeing continuously circulated through the eccentric bearings 24, so thatthe oil lubricates same, and being continuously circulated through theannulus 46 for cooling purposes. Solid contaminants are trapped againstthe inner surface of the eccentric shaft housing 28 so that they cannotenter the tube 51 leading to the eccentric bearings 24. Further, sincethis is a closed system, solid contaminants build up at a very slow rateso that frequent changing of the oil and flushing of the system areunnecessary. These, and the various other advantages and resultshereinbefore set forth in detail, are all important features of theinvention.

If desired, the roller 10, may be filled with water ballast to increaseits weight. Such water ballast also enhances the cooling of thelubricant and air within the eccentric housing 20 by carrying heat byconvection to the roller 10 and its headers 12. If complete orsubstantially complete filling of the roller 10 is not desired from theweight standpoint, a similar water cooling effect can be achieved with asmall amount of water with the structure of FIG. 4. Therein the roller10 is shown as equipped with buckets or scoops 60, which may be anglessecured to the roller periphery, and adjacent ones of which face inopposite directions. With this construction, the roller 10 may contain asmall amount of water 62, which the buckets 60 pick up and drop onto thehousing 20, as indicated at 64, for either direction of roller rotation.Thus, enhanced cooling is achieved with even a small amount of water bycarrying heat to the roller 10.

Although exemplary embodiments of the invention have been disclosedherein for purposes of illustration, it will be understood that variouschanges, modifications and substitutions may be incorporated in suchembodiments without departing from the scope of the invention as definedby the claims appearing hereinafter.

I claim as my invention:

1. In an eccentric system for a vibratory apparatus, the combination of:

a. a tube;

b. bearings respectively supporting the ends of said tube for rotationabout the axis thereof;

0. an eccentric in and spaced radially from said tube and having endscoaxial with and respectively carried by said ends of said tube, withsaid eccentric fixed to said tube; and

d. means for rotating said tube and said eccentric about the axis ofsaid tube.

2. An eccentric system as set forth in claim 1 wherein said eccentric isa bar extending longitudinally of said tube with its center of massspaced radially from the axis of said tube.

3. An eccentric system according to claim 2 wherein said tube isprovided with end closures respectively carried by said bearings.

4. An eccentric system as set forth in claim 3 including a tubular outerhousing enclosing said tube and carrying said bearings in fixed axiallyspaced relation.

5. An eccentric system as defined in claim 3 including an outer housingenclosing said tube and said bearings, and including means forcirculating a lubricant between said tube and said housing through saidbearings.

6. An eccentric system as set forth in claim 5 wherein said lubricantcirculating means includes impellers respectively adjacent said bearingsand rotatable with said tube about the axis thereof.

7. An eccentric system according to claim 6 wherein said end closuresare provided with inlet ports communicating with said impellers andthrough which said impellers pump the lubricant into said tube, and arefurther provided with metering outlet ports communicating with saidbearings for metering the lubricant from said tube to said bearings.

8. An eccentric system per claim 7 including a longitudinal lubricantline interconnecting said metering ports and having inlet portsintermediate its ends.

9. An eccentric system as defined in claim 8 including air dischargeports in said tube for the discharge of air pumped into said tubethrough said inlet ports by said impellers.

10. An eccentric system as defined in claim 4 including means forcontacting the exterior of said outer housing with a coolant.

i l t i

1. In an eccentric system for a vibratory apparatus, the combination of:a. a tube; b. bearings respectively supporting the ends of said tube forrotation about the axis thereof; c. an eccentric in and spaced radiallyfrom said tube and having ends coaxial with and respectively carried bysaid ends of said tube, with said eccentric fixed to said tube; and d.means for rotating said tube and said eccentric about the axis of saidtube.
 2. An eccentric system as set forth in claim 1 wherein saideccentric is a bar extending longitudinally of said tube with its centerof mass spaced radially from the axis of said tube.
 3. An eccentricsystem according to claim 2 wherein said tube is provided with endclosures respectively carried by said bearings.
 4. An eccentric systemas set forth in claim 3 including a tubular outer housing enclosing saidtube and carrying said bearings in fixed axially spaced relation.
 5. Aneccentric system as defined in claim 3 including an outer housingenclosing said tube and said bearings, and including means forcirculating a lubricant between said tube and said housing through saidbearings.
 6. An eccentric system as set forth in claim 5 wherein saidlubricant circulating means includes impellers respectively adjacentsaid bearings and rotatable with said tube about the axis thereof.
 7. Aneccentric system according to claim 6 wherein said end closures areprovided with inlet ports communicating with said impellers and throughwhich said impellers pump the lubricant into said tube, and are furtherprovided with metering outlet ports communicating with said bearings formetering the lubricant from said tube to said bearings.
 8. An eccentricsystem per claim 7 including a longitudinal lubricant lineinterconnecting said metering ports and having inlet ports intermediateits ends.
 9. An eccentric system as defined in claim 8 including airdischarge ports in said tube for the discharge of air pumped into saidtube through said inlet ports by said impellers.
 10. An eccentric systemas defined in claim 4 including means for contacting the exterior ofsaid outer housing with a coolant.